Predictive value of pre-procedural QTc interval for in-hospital major adverse cardiovascular events following primary percutaneous coronary intervention in acute myocardial infarction

Figures

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  Figure 1. Patient selection flowchart. A total of 142 patients who underwent primary percutaneous coronary intervention (PCI) for acute myocardial infarction were initially enrolled in this study. After excluding 19 patients without pre-PCI electrocardiographic records suitable for QT interval measurement, 123 patients were included in the final analysis. MACE, major adverse cardiovascular events.

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  Figure 2. MACE types distribution and interaction between QTc prolongation and diabetes mellitus. (A) Pie chart showing the proportional distribution of different MACE types among patients who experienced events (n = 53). Acute heart failure accounted for 37.7% of MACE, followed by ventricular arrhythmias (35.8%), hemorrhagic complications (24.5%), and cardiogenic shock (1.9%). (B) Bar chart showing MACE incidence stratified by QTc status (>440 ms vs ≤440 ms) and diabetes mellitus status.

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  Figure 3. Distribution of pre-PCI QTc intervals. Histogram showing the distribution of corrected QT (QTc) intervals in the study population (N = 123). The vertical dashed line indicates the 440 ms cutoff value for QTc prolongation. The density curve is overlaid in blue. In the upper right corner, the number and percentage of patients with QTc >440 ms and ≤440 ms are displayed.

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  Figure 4. Comparison of baseline characteristics between QTc >440 ms and ≤440 ms groups. Six-panel box plots comparing the distribution of key baseline characteristics between patients with and without QTc prolongation (>440 ms vs. ≤440 ms). Panels show: (A) Age, (B) Heart rate, (C) Left ventricular ejection fraction (LVEF), (D) B-type natriuretic peptide (BNP), (E) QTc interval, and (F) Systolic blood pressure (SBP). P-values were calculated using the Mann–Whitney U test or independent t-test as appropriate.

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  Figure 5. Forest plot of univariate and multivariate logistic regression analysis for in-hospital MACE. Forest plot displaying odds ratios (OR) with 95% confidence intervals (CI) for predictors of in-hospital major adverse cardiovascular events (MACE). The left panel shows results from univariate analysis, and the right panel shows results from multivariate logistic regression adjusted for pre-procedural heart rate, age, sex, left ventricular ejection fraction (LVEF), and diabetes mellitus. The dashed vertical line represents OR = 1. Variables with P < 0.05 in multivariate analysis are considered statistically significant. The in-figure label “AUC=0.734” in panel B is a typographical error from an earlier model version; the correct multivariate model AUC is 0.767 as stated in the text and Table 2. The figure has been regenerated accordingly.

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  Figure 6. Receiver operating characteristic (ROC) curve for the predictive model. ROC curve illustrating the discriminative ability of the multivariate predictive model incorporating QTc interval, pre-procedural heart rate, age, sex, LVEF, and diabetes mellitus for predicting in-hospital MACE. The area under the curve (AUC) was 0.767. The diagonal reference line represents a non-discriminative model (AUC = 0.5). The optimal cutoff point was determined using the Youden index.

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  Figure 7. Exploratory quartile analysis of QTc and MACE risk. Line plot showing the incidence of in-hospital MACE across QTc quartiles with 95% confidence intervals. Quartile definitions: Q1, 348–416 ms (n = 31); Q2, 419–437 ms (n = 31); Q3, 438–460 ms (n = 31); Q4, 462–619 ms (n = 30). The P for trend was calculated using Cochran-Armitage trend test (P = 0.049). A more conservative test of linear association (point-biserial correlation between raw QTc values and MACE status) yielded r = 0.163 (P = 0.072), further supporting the absence of a linear dose-response relationship. MACE incidence across Q1–Q4 was 32.3%, 32.3%, 58.1%, and 50.0%, respectively. Q3 showed the highest unadjusted OR (2.91, P = 0.044). Note the non-monotonic pattern (Q4 < Q3); the Q3–Q4 difference was nonsignificant (P = 0.611), and this pattern should not be interpreted as evidence of a dose-response relationship.

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  Figure 8. Relationship between left ventricular ejection fraction and QTc intervals. Scatter plot showing the correlation between left ventricular ejection fraction (LVEF) and pre-PCI QTc intervals. Patients who experienced in-hospital MACE are shown in red dots, and those without MACE are shown in blue dots. The linear regression line with 95% confidence interval band is displayed. A weak but statistically significant inverse correlation was observed (r = −0.25, P = 0.005).

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  Figure 9. Subgroup analysis of the association between QTc prolongation (>440 ms) and in-hospital MACE. Forest plot displaying unadjusted odds ratios (OR) with 95% confidence intervals (CI) for the association between QTc prolongation and MACE risk across clinically relevant subgroups. All subgroup ORs were greater than 1, indicating a consistent direction of association. Statistically significant associations were observed in the age <65 years subgroup (OR = 3.00, P = 0.017), male subgroup (OR = 3.07, P = 0.009), and diabetes mellitus subgroup (OR = 4.44, P = 0.047). No significant interaction was found between any subgroup factor and QTc prolongation (all P for interaction >0.30).

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  Figure 10. Representative coronary angiographic images from four typical cases. (A) Pre-PCI angiogram of a 38-year-old male patient (Case 1) with total LAD occlusion and TIMI 0 flow; this patient developed ventricular fibrillation post-PCI with a pre-procedural QTc of 526 ms. (B) Post-PCI angiogram of a 51-year-old male (Case 2) showing restored TIMI 3 flow after successful LAD recanalization; this patient experienced post-PCI ventricular fibrillation despite successful reperfusion, with a pre-procedural QTc of 470 ms. (C) Pre-PCI angiogram of a 54-year-old male (Case 3) with partial RCA occlusion and TIMI 1 flow; no MACE occurred during hospitalization (QTc 358 ms). (D) Post-PCI angiogram of a 76-year-old female (Case 4) demonstrating restored TIMI 3 flow after LAD intervention; no in-hospital MACE (QTc 619 ms). Red arrows indicate culprit lesion sites. Cases were purposively selected to span the observed range of TIMI flow grades, culprit vessels, and MACE outcomes; they are not a random or representative sample and are presented for descriptive illustration only.